Secure integrated circuit cards, commonly referred to as smart cards, may be of the form of an embedded integrated circuit hardware device that is small enough to fit into a user's pocket. Secure integrated circuit cards may be used in many situations where critical information must be stored and shared. For example, set-top boxes that facilitate pay-per-view or video-on-demand features may use a secure integrated circuit card to supply user account information to a provider along with a request for access to such features, and to subsequently decrypt encrypted digital video streams that may be provided in response to the request. As another example, a Subscriber Identity Module (SIM) card in a Global Systems for Mobile Communications (GSM) phone may be used to store a user's personal information, such as his or her phone book, device preferences, preferred network(s), saved text or voice messages and service provider information. A SIM card may allow a user, for example, to change handsets while retaining all of his or her information on the SIM card. Smart cards may be used in a variety of applications (e.g., electronic payment systems, including specialized auto-debit devices such as public transportation cards and personal identification documents, such as passports, drivers licenses, and medical identification cards).
Typically, smart cards send and/or receive data by communicating with an appropriate reader system. Some cards, commonly called contact cards, communicate with reader systems when the card makes direct electrical connection to a reader system. Data signals communicated over such direct contact interfaces may conform to a particular communication protocol, such as ISO/IEC 7816 or ISO/IEC 7810 (ISO refers to the International Organization for Standardization; IEC refers to the International Electrotechnical Commission). Other cards, called contactless cards, can communicate wirelessly with reader systems using RF (radio frequency) signals. RF data signals used by a contactless card may conform to a particular communication protocol, such as ISO/IEC 14443 or ISO/IEC 15693.
Various types of power sources may supply the electrical power used to operate the circuitry in an integrated circuit card. For example, some cards are powered by an integrated power storage device, such as a battery or large value capacitor. Contact type cards can be powered by making direct electrical contact with terminals connected to a power source, which may be, for example, a power supply that is integrated in a reader system. Contactless type smart cards may be powered by capturing and storing radio frequency (RF) energy transmitted by a reader system.
A hybrid type of smart card, sometimes called a combination card, can exchange data through either direct electrical contact or RF coupling to a reader system.